Method of treating old wells.



W; 0. SNBLLING. METHOD 0F TRATING OLD WELLS.

AryLIoATIoN FILED AUG. 2, 191s.

Patented July 21, 1914;

l INVENTOR.

M@ fix BY I ,@7141 f/f' ATTORNEY..

UNITED sTATEs PATENT oEEIcE.

METHOD F TREATING OLD WELLS.

Specification of Letters Patent.

Patented July 21, 1914.

Application l'ed August 2, 1913. Serial No. 782,695.

. To all whom it may concern Be 1t known that I, WALTER O. SNELLING, a citizen of the United States, and a resident of Pittsburgh, county of Allegheny, State of Pennsylvania, have invented certain new' and useful Improvements in Methods of Treating Old Wells, -of which-the following is a description.

My invention relates to a methodvoftreating old wells, particularly old oil andl gas wells, for the purpose of rejuvenating and increasing the yield of the'same.

-It is well known that the porous' forma tions in the vicinity of oil and gas wells, constituting'the oil or gas-bearing strata, such as sandstone, etc., gradually becomeclogged by paraiin and tarry matters, because of whichthe flow and production of a well slowly decreases. Various efforts have been made from time to time to find effective methodse for removing such obstructions. The efficiency of heat in this connection has long been recognized, and the introduction within the bore-hole of a well of electric heaters, steam, burning gas, etc., have been described. By Suchmethode it is possible 'to heat up the lower part of a' borehole, so as 'to melt part of the clogging hydrocarbons. I believe, however, that by none of these proposed methods is the heat produced suiiciently intense, nor does itl penetrate far enough through the obstructin material to achieve any great measure o success. It may also be-'noted that the process of firing a large charge ofnitroglycerinjwithin an oil well, with detonation, iswell known,by which means thev rock in the vicinity is fractured and ,fissured This is usually done in the case of new wells, to open up 'fractures through which the o'il can find more ready access to the well; the ringof nitroglyc'erin` has however' also been employed to restore wells clogged by para-Hin or tarry matters,

`vhowever, a well .is

the shattering eHect ofthe explosion producing open channels or fissures throughthe' clogged material, extendingy sufficiently far into uncloggedmporous material to enable vaflow of oil to again be obtf'iined. When, shot with nitroglycerin, the impervious clay capping, overlying the .porous oil-bearing formation, is often frac' tured, in which case the oilworks through `the fractures and'is lost forever. A'

My present invention consists in a new and greatly superior method for removing mixture, as of a combustible agent `and a' supporter of combustion, as a result of which there are evolved large volumes of highly heated gas under great pressure, the borehole of the well being closed at the time to` prevent the .escape of the heated gases evolvedsand to enable the requisite pressure to be reached. By such methods I find I can 'melt and drive away to a considerable dist-ance the deposited paraffin and tarry bodies, arid since the gases are evolved with comparative slowness and. without violence, there is no fracturing effect, 'the gases evolved acting entirely to melt, dissolve and push before them the Vparatiin bodies, made fluid by the high temperatures produced.

The object of my invention is accordingly to increase the yield of a well by decomposing, melting, volatilizing orv otherwise relmoving from the vicinity of an old well, the clogging bodies described, by burning a nondetonating explosive mixture within a closed well, or by otherwise evolving or introduc' ing within la well, in a comparatively slow and non-violent manner, gases of such high temperature and pressure as to be capable of producing the desired effect.

In order that ma' invention may be more easily comprehen ed, attention is hereby .directed to the accompanying drawing, forming part ofthis specitication, and illusvention.

In the drawing, the figure represents a vertical cross-section, partly broken away, through a Well equipped with means for .carrying'out one form of my process.

the'efiicient carrying out ofmy process that v the 'bore'hole should be closed by some form of plug, to prevent the escape of the heated gases, and to enable ,the requisite pressure trating one manner of carrying out v'my i-n- As I'Jh'ave stated, I deem it essential toto bereached. Thisma be accomplished in any desired manner, as y capping the well, or by inserting into the tubing of the welll an expandible member capable of being forced tar4 and other materials which may tightly against the walls of' the well, and` Y pressure to be reached.

, stance,

Vable to resist a pressure from below, and yet sudden metio-n, enables the requisite After removing paraffin and tarry matters, in the manner described', the stemming or tamping material may be removed byl drilling through same, or in any other suitable way. t

In its simplest form m invention 1s earried out by placing wit in the well, and preferably at its bottom, a suitable slowburning mixture, which may b e contained in' a suitable tube or vesseltogether with a fuse or other suitable means for igniting the same, without deto-nation. l

vReferring to the drawing, thevwall of the' wel-l, partly broken away to indicate greatf length, isrepresented by the'referencecharacter 1, the bore hole 4tapping `the porous sandstone or other oil `bearing stratum 2, which'is represented as being covered by an upper shale-like, non-porous layer'.-

At 4 l have represented aplug closing the bore hole to retain the gas produced, this. plug being of any suitable character, suchas a packing placed in the bore hole after 'cheil gas evolving mixture has, been lowered therein. placed above the well; The gas evolving, mixture isv represented as contained in thev vessel. 5 which may be of anysuitable char` acter', such as a can provided with a fuse 6, which is lighted before the vessel 5 is lowance to ered into the well.

A snearl all wells are l shot with nitroglycerin w en lirstbrought in, I have shown'g lower part of the Wella large 'irregul lar chamber 7 representing the 'hole -madeg by the nitroglycerinfrom which hole theg cracks and ssures 8, made when the nitro#E glycerin was fired, are represented as-,eX- tending. 4

The combustible mass which I useis'af" selfontained source of heated gases, con-y sisting of combustible compounds and the,

oxygen'required for the combustion of such;

compounds, or otherendothermic chemical; mixture orcompound, capable ofy undergo -ing change with the evolution of fhigh'lyf vheatedsgases under pressure, andpreierahly it is a pyrotechnic mass conslsting omtrated organic bodies, sothat itsl "product-s of. combustion will not include solid residuei By the term pyrotechnic mass I- mean-ai.

slow burning .mixture or compound whichl a combustible chemical reactions brought about inf'schfay which through its inertia, or resist-v Orif desired, a cap 4 may be;v

pyrotechnic mass. The mixture may comprise "an explosive similar togun powder, thermit mixed with suitable gas-evolving materials, or other chemical mass whicln-,by fusel or other initiating means, will produce a large -volume of hot gases, under high pressure, the evolution of gases taking place. slowly and regularly. I may use a mixture consisting of metallic nitrates with charcoal and sulfur, and in manyl cases this will be found tobe highly desirable. Usually, however, a still moredesir-able material for use will be nitrated cotton, nitrated starch, or even nitro-glycerin. Itshould be particularly noted, however, that such bodies, if u sed, are to be used as simple combustible mixtures, myv invention being concerned with the use o a hon-detonating explosive mixture, for the purpose and because of the reasons labove noted. Nitro celluloses and other nitrated organic compounds are well known as detonating materials, and their useto rend and fissure the rock intor edoing oil wells is well known. The use of hese explosives when exploded with detonation isd outside the scope of my invention, in which, however, such substances may be employed as sources of heated gas under high pressure. Nitrh cellulose burns, when simply vignited by flame as contemplated by me, but.

never detonates, and to bring about its detonation a primer is required, consisting yof fulminate of mercury, or' other compoundY detonating-by contactl with flame, and no detonating means is employed in my invention.

In another form of my -invention a cons1derable lmass-of heat-evolving mixture, such: as thermit, for example, is lowered to'- the vbottom of the -well and chemical 'reaction'is started within the same. The .well -being closed, as stated, I then force steam, air, or suitable gas, under pressure, into, the boro hole.. This may be accomplished by 'any suitable means such as by lthe connection. 9,

indicated inthe drawing connecting the interior of the bore hole below cap 4"' or plug 4 with a steam pump or other means for forcing steam or a, neutral gas underl pressure down the bore hole.' The gas so introduced becomes greatly superheatei on passing through or into the proximity ofi-fthe heat-evolving member or mixture, and passing `outward throughl the' .porous stratajjhas the dissolving and paraiiinremoving action already described.4 It is not 'absolutely es-y sential, in practising this form of my `1nventiOn, that 'the' heat-producing mass shouldvbe located at the bottom ofthe well,

-since it could, jwith very fair results vbe located, in the upper, part ofthe closed well.

It is obvious that by my in'vention a regular and, controllable e'ect is z produced,

ture to be'burned can bedeeided upon and that the amount and. nature ofthe mix-l` accordance With the heat, pressure, etc.

. called for by the local conditions.

Vhile I have described my invention particularly with reference to yoil Wells, it is obvious that it is also applicable to the treatment of gas Wells, and to other Wells in Which the same or similar ditliculties arise, ldue to the clogging or obstruction of formations or passages Within the earth, or to situations generally in which it is desirable t-o dissolve or remove substances near the bottom of the Well by heat and pressure, Without rending or fracturing the surrounding formations.

In practising the invention, the Well Will be kept closed until a sufficient time has elapsed for the heated gases to penetrate the clogged formations, or until the pressure in the Well has greatly decreased, showing thatv the gases have largely escaped through the rock, and exercised its obstruction removing functions in so doing. It is also y obvious that it is not necessary for the clo- Sure of the Well to be at the top, although in most cases it Will be convenient to close the Well at the top. The Well may be closed at any distance below the surface, and above the gas-evolving mixture, or section to be heated.

Having now described my invention What I claim and desire to protect by Letters Patent is f 1. `The method of treating old Wells, which `consists in closing the Well and producing the gas so produced will, in passingvoutvvard from l@he Well, tend to melt, dissolve, thermolize, decompose orotherwise remove paraiin and other bodies obstructing the -pores or liassages of the formation adjacent to the we 2. The-method of treating old Wells, which consists in. closin the Well land burning thereinv Without etonation a pyrtechnic mass or mixture to produce a considerable volumil of highly heated gas under pressure,

d and keeping the well closed lfor a sufficient time 'to enable the gas-soproduced to largely pass out'through the pores or passages of Athe surrounding formation, and exercise a volatilizing melting or removing action on` -V vparaffin or other obstructions in suchv pores or passages.

violent acceleration, until the maximum is' reached, and keeping the Well closed for a sulicient time to enable the hot gas to penetrate the Walls of the closed space "and melt, dissolve or push aside bodies in its path.

4. The method of treating old Wells, which consists in causing the production of a large body of highly heated gas under pressure, within a closed Well, by chemical reaction," Without detonation, Within a pyrotechnic mass comprising combustible compounds and the oxygen required for their combustion, such gas exercising a melting or removing actiononparalin or other obstructions in the porous formations adjacent to the Well.

5. The method of treating old Wells, which consists in causing the production of a large body of highly heated gas under pressure, Within the Well, by the combustion of a considerable quantity of a non-detonating explosive mixture vcomprising; nitrated organic bodies, which gas is capable of penetrating the porous formations adjoining the Well and melting or removing parain and other obstruct-ions therein. f v l '6. The method of treating old Wells,Wh1ch consists in causing a chemical reaction in a considerable mass of a heat-evolving mixture, Within a Well, closing the Well and introducing Within the closed Well and into the proximity of such mixture `a .suitable gas under pressure, ucapa-ble When highly heated of penetrating the adjoining porous formations and melting or removing paraffin therein.

7. rilhe method of treating old Wells, Which consists `in bringing about Within such a- Well,.While closed to the atmosphere, a chemical reaction Within a .non-detonating endothermic chemical compound or. mixture, capable of evolving highly heated gases under pressure. I

This speciiicationsigned and witnessed.

this'31'st day of Ju1y-1918.

y, WALTER O. SNELLING. Witnesses: l

A.n J. PHILLIPS,

MAY WILLIAMS. 

